Services in computer networks may be provided using a collection or “cluster” of computers, for example to support a large number of users and the accompanying high rates of service communications and operations or to provide extra resistance to malfunctions and reliability of service. A clustered set of computers is typically interconnected by a private network having one or more attached gateway devices providing path(s) to external network(s) to which the users of the service are connected. Such external networks may include the public internet, for example. The private network may be constructed and organized using any of a variety of network technologies, including one or more local area networks (LANs). A LAN may include a collection of switches that operate to receive and forward network traffic at a data link layer, or layer 2, of network operation according to well-known OSI model. The clustered system typically interacts with the external network(s) at a network layer, or layer 3, of network operation, which includes use of specialized devices and protocols providing message routing across wider areas and arbitrary connection topologies.